body {
    margin: 20px 10px;
    padding: 0;
    font-family: helvetica, sans-serif;
}

#left {
    float: left;
    width: 30%;
    padding: 0 0 0 20px;
}

#right {
    float: right;
    width: 65%;
    padding: 10px;
    /*background:#efefef;*/
    height: 100%;
}

#cases {
    width: 100%;
    overflow: auto;
    font-family: helvetica, sans-serif;
}

#form {
    float: none;
}

p#back-to-top { 
    position:fixed; 
    display:none; 
    bottom:60px; 
    right:80px; 
} 
p#back-to-top a {
    text-align: center;
    text-decoration: none;
    color: #d1d1d1;
    display: block;
    width: 64px;
    /*使用CSS3中的transition属性给跳转链接中的文字添加渐变效果*/
    -moz-transition: color 1s;
    -webkit-transition: color 1s;
    -o-transition: color 1s;

}
p#back-to-top a:hover {
    color: #979797;
}
p#back-to-top a span {
    background: transparent url(top_01.png) no-repeat center center;
    border-radius: 6px;
    display: block;
    height: 64px;
    width: 64px;
    margin-bottom: 5px;
    /*使用CSS3中的transition属性给<span>标签背景颜色添加渐变效果*/
    -moz-transition: background 1s;
    -webkit-transition: background 1s;
    -o-transition: background 1s;
}
#back-to-top a:hover span {
    /*background: transparent url(top_02.png?1202) no-repeat -25px -290px;*/
    background: transparent url(top_01.png) no-repeat center center;
}